The South African Water Act (Act 36 of 1998) (NWA, 1998) requires the calculation of the amount of water required for ecological sustainability in aquatic systems. Part of this process is the classification of slopes according to geomorphological class, which in turn requires, inter alia, the derivation of river longitudinal profiles from which to calculate these slopes. This has prompted the need to develop a method for obtaining these slopes that is fast and repeatable, and can be applied at both a national as well as sub-catchment level. Input data sets are required that are consistently available at a national as well as a sub-catchment level. This study will assess the results of using a semi-automated GIS procedure to derive longitudinal river profiles and slopes, based on nationally available data sets, in a test catchment. In recent years the use of Digital Elevation Models (DEMs) is replacing contour lines on topographic map sheets as the source of elevation inputs required to construct longitudinal profiles. The main question put forward is: can river longitudinal profiles and slopes generated from a DEM and based on 1:500 000 mapped river lines adjusted to within 50m of 1:50 000 mapped river lines, be used as effectively as river longitudinal profiles extracted from 1:50 000 mapped contours and based on 1:50 000 mapped rivers lines? Primary catchment X, situated in eastern South Africa, is used as the test area for this study. River channels in this catchment represent a range of slopes, from steep mountains streams to flat lowland rivers. The assessment is undertaken on 109 rivers identified at 1:500 000 scale in primary catchment X. These river lines are based on those originally scanned and vectorised from 1:500 000 topographic map sheets. These lines are available at a national level, have been connected to form a continuous network and horizontally adjusted to improve locational accuracy to within 50m of the river lines on 1:50 000 topographic map sheets (DWAF, 2003; DWAF, 2006). Profile elevation values extracted from three medium to low resolution Digital Elevation Models are examined in this study. This study compares slopes based on the elevation values extracted from DEMs according to adjusted 1:500 000 river lines, to those extracted from contour lines on 1:50 000 topographic map sheets according to 1:50 000 scanned river lines. These input data sets and any limitations associated with them are discussed. A semi-automated method used to extract and compile the elevation and distance values required to construct longitudinal profiles and the statistical tests and procedures used to compare elevation and slope values, are also described. Comparisons are formed around two reference scenarios. In the first elevations are extracted at the intersections of river lines with 1:50 000 scanned contour lines. The second reference scenario uses these same derived longitudinal profiles, but divided into five sets of equal horizontal intervals: 100m, 200m, 300m, 400m and 500m. Finally, the conclusions that can be drawn form these results, together with any recommendations for either improving or even replacing the data sets and methods described in this study, are presented. It is found that, that when comparing slopes derived from 1:50 000 contour line elevations to those based on DEM elevations, steep slopes tend to be more underestimated by the DEM than flatter slopes. More than 90% of profiles based on contour intervals and more than 90% of slopes derived at 500m horizontal distance intervals show no significant difference between slopes. It is finally suggested that the adjusted 1:500 000 river lines available from DWA (DWAF, 2003; DWAF 2006) combined with elevations from medium to low resolution DEMs can be used as a substitute for 1:50 000 river line and contour linebased profiles. It is also suggested that the automated GIS procedure used to extract and combine these values can be applied in other areas where the 1:500 000 river lines and medium to low resolution DEMs are available.

L’aménagement des villes á industrie extractive dans la zone subarctique amène des problèmes complexes. Ces agglomérations urbaines, liéees á l'industrie minière, forestière, pétrolière ou hydro-électrique affichent des caractères personnels qui les identifient. Si leurs caractères, leurs raisons d'être, leur administration et leur gouvernement municipal et leur législation diffèrent dans les diverses parties du Canada, elles présentent toutefois les mêmes grands problèmes. La province de Québec offre en Schefferville, Chibougamau et Chapais trois exemples de ces villes minières subarctiques. L'étude de leur milieu géographique fait ressortir les problèmes á résoudre dans leur aménagement.

A theoretical relationship between the variance of height (geopotential) and the variance of the geostrophic wind was tested in the Arctic at 500 mb. As had been expected, a high correlation was found to exist between these two quantities although the form of the relationship (linear in the logarithms of the standard deviations of height and wind) was totally unexpected. The Arctic data from previous papers, concerned with the relationship between the time variances of height and wind, were then reanalysed and the relationship between them was found to be of the same form as for the space variances. In both cases the standard error of estimate was too large to be able to calculate accurately the wind variance from the height variance, but the relationships do allow climatological estimates of the mean kinetic energy and the size of the dominant wave systems.

A series of research workers in the Department of Geography at McGill University have for several years been engaged in a study of the physiography and plant geography of Quebec-Labrador. The principal results of this study up to the present are two series of reconnaisance maps of the physiographic surface-type and the cover-type, usually the plant-cover. [...]

Pulp and paper manufacturing is one of Canada's best known industries, but the spectacular woods operation of British Columbia seem largely to overshadow the equally significant forest industries of eastern Canada, particularly in popular accounts of Canadian manufacturing. It was therefore with great interest and some trepidation that the writer approached the problem of preparing a thesis on a topic which was to him, a new arrival from England, beyond the range of his experience or knowledge.

The development of hydro-electric power is of paramount importance to the Province of Quebec. There are no coal deposits in the Province, oil has not, as yet, been found, and natural gas has appeared only in limited quantities; therefore, water power, the white coal, must be relied upon to supply the power required for industrial development. Electric power output is often considered an index of industrial growth. In 1900, prior to the inception of long-distance transmission of electricity, Canada's economic basis was agriculture, and the total hydraulic installation was about 173,000 horse power.

One need only see a glacial map of North America to become aware of a curious, if not anomalous fact. For of all the continental vastness four times-buried under the great ice sheets of the Pleistocene epoch, only one land area of any size remained ice free. That was the area of central Alaska and the western Yukon Territory. Here is to be sought the most complete climatic and stratigraphic record of Pleistocene events on the continent, north of the southern border of ice. Within this area, one is fortunate to find a road and transportation network which makes it accessible to the field worker as no other place in North America so far north.

The complete record of the first two years of radiosonde observations from the Polar Basin have been analyzed with respect to thermal inversions. An objective classification system was introduced to permit exact determinations of type, magnitudes of component layers, and frequencies of occurrence, of inversions. The method has general applicability to other portions of the radiosonde ascent. A new unit of inversion intensity was introduced and appears to be an improvement over the use of lapse rate.

A classification of airflow pattern types is formulated for the region on the basis of synoptic weather maps for November, 1956 to March, 1958. Regional indices of the zonal and meridional flow at mean sea level and the 500 mb level are examined in relation to the airflow types. The spatial and temporal variations of weather phenomena associated with the types are analyzed by quantitative weather parameters and the significance of the results is assessed with reference to local weather forecasting and palaeoclimatic reconstructions.

Investigation of the structure and the behavior of the arctic atmosphere to any great extent has only recently become possible. Meteorological research has been hampered by the lack of upper air data resulting from a thin network of arctic radiosonde stations. However, since 1945 there has been an increasing interest in the Arctic, and a subsequent expansion of the radiosonde station network. This fact, together with the International Geophysical Year program, has stimulated much more research.